Processing and fitting of sealing surface of battery shell frame mold

Processing and fitting of sealing surface of battery shell frame mold
The sealing surface of the battery case requires Ra1.6 and a flatness of 0.1mm. The key to the mold lies in the processing sequence, blade direction, and cleanliness.
Three quantitative indicators of sealing surface
The surface roughness Ra1.6 is a common requirement, and some projects have tightened it to Ra0.8. The finer the roughness, the more thorough the infiltration of the sealant.
The flatness is usually controlled at 0.1mm, and the length is converted to 0.3mm/m. Only when both flatness and roughness meet the standard can the seal be reliable.
The dimensional tolerance of the sealing groove is usually taken as ± 0.1mm. If the groove width exceeds the tolerance, the compression of the rubber strip is insufficient, and the risk of water leakage increases.
The processing sequence cannot be reversed
The correct order is: rough machining, stress relief, semi precision machining, and precision machining. Save stress, the surface after precision machining will slowly deform.
It is recommended to leave a rough machining allowance of 2-3mm. If the allowance is too small, it cannot eliminate the surface defects of the blank; If it is too large, the cutting stress will increase.
Natural aging or vibration aging is required before precision machining. Natural placement for more than 48 hours significantly improves dimensional stability.
The direction of the knife pattern affects the sealing effect
The tool path during precision machining should be consistent with the direction of the sealing groove. Horizontal blade lines will form microchannels, which are prone to leakage along the direction of the blade lines.
It is recommended to use a round nose knife as the final light knife, with a step distance controlled between 0.1-0.2mm. If the step distance is too large, the residual height on the surface will exceed the standard.
Xinfeng Mold will mark the cutting direction requirements on the sealing surface processing of the battery case frame mold to avoid cutting along the conventional path at the processing end.
The cleanliness of the mating surface is easily overlooked
The residual aluminum shavings or oil stains on the sealing surface will press out pits during mold closing. A pit depth of 0.05mm is sufficient to form leakage.
After processing, deburring and ultrasonic cleaning are required. The recommended temperature for the cleaning solution is 40-60 ℃, and the cleaning time should not be less than 5 minutes.
Wipe with a dust-free cloth before assembly and conduct a visual inspection. This step is not time-consuming, but it can avoid a lot of rework.
Coordination between mold and workpiece
The fitting clearance of the sealing surface should be controlled at 0.02-0.05mm. If the clearance is too large, the rubber strip will be squeezed into the clearance and the compression amount will be insufficient.
The mating surface needs to undergo a red lead inspection, and the contact spot area should not be less than 75%. Uneven spots indicate problems with flatness or rigidity.
The support point of the mold should be located near the sealing surface. The support point is far away from the sealing surface, and the sealing surface will open due to the cantilever effect when the mold is closed.
Detection method
Use a portable profilometer to measure roughness, taking 3-5 points per meter. Single point qualification does not represent overall qualification.
The flatness is initially checked with a ruler and a stopperer, and then rechecked with a three coordinate or laser flatness meter. When there is a significant difference in the results between the two methods, the three coordinates shall prevail.
The airtightness test is the final verification. The part level test pressure is 10-30kPa, and the pressure is maintained for 30 minutes. The leakage rate is executed according to the drawing.
Frequently Asked Questions
Q: What is the required roughness for the sealing surface?
Answer: Common Ra1.6, some projects require Ra0.8.
Question: How to control flatness?
Answer: Commonly 0.1mm, long pieces are converted to 0.3mm/m.
Q: Can the processing sequence eliminate stress?
Answer: No, the precision machined surface will slowly deform after being omitted.
Q: Are there any requirements for the direction of the blade pattern?
Answer: It should be aligned with the direction of the sealing groove to avoid horizontal knife marks.
Q: How much is the clearance for coordination?
Answer: Suggest 0.02-0.05mm, balancing sealing and assembly.
Q: How can cleanliness be guaranteed?
Answer: Deburring and ultrasonic cleaning, wipe and inspect before assembly.
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